Abstract:Objective To evaluate the effects of levothyroxine(L-T4) on benign thyroid nodules.Methods Three databases were searched to obtain reports on the effects of L-T4 on benign thyroid nodules:PubMed(1998-2011),Wanfangdata(1998-2011) and China Proceedings of Endocrinology Cnference(January 2005-December 2010).The main inclusion criteria were as follows:randomized controlled trial(RCT);solitary or multiple substantial nodules proven by ultrasonography;benign lesion proven by biopsy;thyroid function in the normal range;all treated by L-T4;at least 6 months of follow-up.Results Five randomized trials were included(353 subjects).The effects of L-T4 on thyroid nodule volume were analyzed with the fixed effect model.Compared with controls,thyroid nodule volume was decreased by 0.51 mL by treatment with L-T4(95% confidence interval,0.11-0.90,P=0.01).No cardiovascular adverse reactions occurred in all cases.Conclusion L-T4 can effectively decrease the benign thyroid nodule volume.